Git Kung Fu: Mastering Git with Rebasing, Cherry-Picking and More

Get IT right
Git Kung Fu
Bartosz Majsak (@majson), Thomas Hug (@gizmoo360)

http://ctp.com
http://github.com/ctpconsulting
1

© 2013 Cambridge Technology Partners
Copyright © 2013 Cambridge Technology Partners All Rights Reserved. Cambridge, its logo, and Get IT Right are trademarks of Cambridge Technology Partners.

About Us


Bartosz Majsak
 Java

Developer by day
 Open source junkie by night (Arquillian core team member)
 Conference speaker by passion (Devoxx, Jazoon ...)



Thomas Hug
 With

Cambridge Technology Partners since 2002
 Java Developer, TTL, Solution Architect
 Apache Committer, OSS contributor and aficionado

2


10/25/2013

Git Concepts



Performance and Efficiency



3

No Central Server – Distributed VCS

Robustness


10/25/2013

Git Internals


Git Architecture


Plumbing and Porcelain
 Composition

of low-level commands into high-level ones
 Unix design principles


Local as much as possible
git-add
git-commit
…

git-diff-index
git-update-server-info
git-check-ref-format
…
5


10/25/2013

Git Storage


Delta storage vs. Directed Acyclic Graph (DAG)
C1

File A
Delta Storage
(SVN, Mercurial,…)

C2

C3

D1

C4

C5

D2
D1

File B

D2

File C

A1

A1

A2

A2

B

B

B

B1

B2

C

6

D2

A
DAG Storage
(Git, cp -r, …)

D1

C1

C2

C2

C3


D3

10/25/2013

Git Storage – Object Model (1)


Git tracks content, not files



Content identified by 40 character SHA1 hash
 Modified

content easily identifiable
 Immutable in the object database


Objects: Blob, Tree, Commit, Tag



References: HEAD, Tags, Remotes
 Mutable,

pointers to commits

Empty directories are not considered as content.
Add an empty .gitignore if you need a folder tracked.

7


Git Storage – Object Model (2)

├── lib
├
├── inc
├
├
└── tricks.rb
├
└── mylib.rc
└── README

8


Git Storage – Local Repository


The repository .git directory

$ cd .git
$ tree -L 1
├── branches
├── config
├── description
├── HEAD
├── hooks
├── info
├── objects
└── refs
9

# Pointers to branches
# Repository local configuration
# Repository description

# Pointer to HEAD in current branch
# Pre- and post action hooks
# Additional information about the repository
# Object database
# Pointers to branches


10/25/2013

Rewriting History


Rebasing
$ git checkout master
$ git rebase mybranch

Rewriting history: Interactive rebase last four commits
$ git rebase --i HEAD~4

11


git rebase

All your base are belong to us
Objectives: Learn how interactive rebasing works.


Experiment with interactive rebase on selected branch
 Reword

commit messages
 Combine commits into one

$ git rebase –i [commits range]

12


10/25/2013

Cherry-pick
$ git cherry-pick [-x]

$ git cherry –v <other_branch>
Lets you check if given commit from other branch
has been already applied on the current branch

13


Feature

Cherry-pick „replays” arbitrary commits onto
your current branch.

10/25/2013

Filter branch
$ git filter-branch



14

Removing a file from every commit
Changing commit metadata globally


10/25/2013

Recovering from Mistakes


Typos
Is there a way to fix poor commit messages?
$ git commit --amend
$ git rebase --i HEAD~X

16


10/25/2013

Fixing Commits and Staging Area
For not yet pushed commits:
$ git commit --amend
Unstage a file:
$ git reset HEAD file.txt
Discard local changes:
$ git checkout -- file.txt
Fully revert to a previous commit:

$ git reset --hard HEAD

17


git reset

Revert
$ git revert HEAD|hash|parent

Upgrading Library

Revert ‘Upgrading Library’

18


git revert

One bridge too far
Disaster recovery.
What if...
$ git reset --hard HEAD^
$ git reflog
$ git reset --hard HEAD@{X}

19


10/25/2013

Who broke the build?!
$ git blame FILE
$ git bisect start
$ git bisect bad
$ git bisect good <HASH>

20


git blame
git bisect

Who broke the build?! - Pickaxe
$ git log –S'search_term' [-p] <resource>
$ git log –G'regex'

git log –S|G

--name-status
--pickaxe-all

21


Sharing without network


Archives
$ git archive --format zip --output "repo.zip" master

git archive

23


Bundles
git bundle
$ git bundle create
../jazoon.bundle master HEAD
$ git bundle create <filename> <refs ...>
$ git bundle create ../jazoon.bundle
--since="one week ago" master
$ git bundle verify /tmp/jazoon.bundle
$ git pull /tmp/ejmr.bundle master:master

You can also add a bundle as a remote:

$ git remote add bundle /path/to/bundle.bundle

24


Repeat Yourself
Repeat Yourself
Repeat Yourself


Reuse Recorded Resolution (ReReRe)
$ git config rerere.enabled true
… # create a merge conflict
git rerere
$ git rerere status
$ git rerere diff
… # resolve conflict
$ git rerere diff
… # commit, reset hard HEAD^1, redo merge

Evict old recorded resolutions from repository:
$ git rerere gc

26


10/25/2013

Other tricks


Sparse Checkouts
$ git init
$ git config core.sparsecheckout true
$ echo path/to/checkout
>> .git/info/sparse-checkout
$ git remote add -f origin ...
$ git pull origin ...

You can also push to sparse checkout repositories

28


10/25/2013

Orphan Branches

??

$ git checkout --orphan [branch]
$ git rm -rf *
Use for:
 Documentation (combine with hooks or CI server!)
 Resources

Have a look at the GitHub gh-pages for some ideas
what orphan branches can do.

29


10/25/2013

Notes
Annotates existing commits.
$ git notes add HEAD
$ git notes add –m’Fixes everything’ HEAD
$ git notes --ref=jazoon edit master~1
$ git push origin refs/notes/jazoon

30


10/25/2013

Other goodies
$ git diff --word-diff --color-words
$ git config --global help.autocorrect 1
$ git rebase -i --autosquash HEAD~3
Commit message should contain squash! or fixup! as message prefix and
title or hash of target commit

31


10/25/2013

Hooks


Git hooks
$ cd .git/hooks
Client-side
 pre-commit
 prepare-commit-msg
 commit-msg

 post-commit

Server-side
 pre-receive
 post-receive
 update

33


10/25/2013

Workflows


Git Flow
$ git flow init
master

35

hotfix

release

git flow
develop


Feature branches

Git in the Enterprise


Get IT right
Thank you!

37


Credits


38

Icons provided by Icons8: http://icons8.com/


10/25/2013

Git Kung Fu: Mastering Git with Rebasing, Cherry-Picking and More

Recomendados

Recomendados

Más contenido relacionado

Destacado

Destacado (16)

Similar a Git Kung Fu: Mastering Git with Rebasing, Cherry-Picking and More

Similar a Git Kung Fu: Mastering Git with Rebasing, Cherry-Picking and More (20)

Más de jazoon13

Más de jazoon13 (17)

Último

Último (20)

Git Kung Fu: Mastering Git with Rebasing, Cherry-Picking and More